1. Field of the Invention
The present invention relates to mobile electronic equipment with a photographing function, such as a digital camera, a cellular phone, and soon. In particular, it relates to a battery check after electric power is supplied to the unit.
2. Description of the Related Art
In a digital camera, when electric power is supplied by the operation of a power button, a program is read from a memory such as a ROM. Then, a boot or startup process, which includes an initial driving of the imaging system and an acquirement of information stored in a removably attached memory card, is carried out. After that, the camera is ready to carry out an imaging operation of a subject. The imaging system, including an image sensor and a photographing optical system and circuits, should be actuated to an initial setting immediately after the electric power is turned on. Therefore, to confirm whether the camera can boot up, a check process to check the remaining battery level; namely, the remaining voltage level, is carried out when the electric power is turned on.
To allow the camera to shoot as soon as possible after the electric power is turned on, for example, firstly only a program necessary to boot up the imaging system is read from the memory, and then a program necessary for other processes is read. However, since the battery check involves a process that inputs or applies a voltage to a suitable load such as a motor, the total boot time taken to prepare the camera for an imaging operation becomes relatively long. On the other hand, to prevent from the camera stopping while the imaging system is being set to the initial setting, it is necessary to check the battery level at the time that the electric power is turned on.